Tracer control mechanism



Jan. l0, 1956 A. H. DALL ET AL TRACER CONTROL MECHANISM Filed May 20, 1952 2 Sheets-Sheet 1 A. H. DALL ET AL TRACER CONTROL MECHANISM 2 Sheets-Sheet 2 ATTORNEYS Jan. l0, 1956 Filed May 20, 1952 United States Patent O 2,730,129 TRACER CoNTRoL MECH/mism Albert H. Dall, Cincinnati, and Hans Fritschi, Amber-ley Village, Ohio, assignors to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Application May 20, 1952, Serial No. 288,806

7 Claims. (Cl. 137-622) This invention relates to pattern controlled machines and more particularly to automatic tracer control mechanisms therefor.

One of the objects of this invention is to improve the construction of tracer control mechanisms to obtain better pressure conditions between the tracer and the pattern.

Another object of this invention is to provide an irnproved tracer control mechanism for simultaneous three direction control between a tool and work piece in pattern controlled machines.

A further object of this invention is to provide a tracer control mechanism in which the weight of the tracer control valve is independent of and bears no relation to the tracer linger pressure on the pattern.

Other objects and advantages of the present invention should be readily apparent by reference to the following specication, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Referring to the drawings in which like reference numerals indicate like or similar parts:

Figure 1 is a sectional elevation through the tracer head which is illustrative of one embodiment of the invention.

Figure 2 is a detail section on the line 2 2 of Figure 1.

Figure 3 is a sectional view taken on the line 3 3 of Figure 1.

Figure 4 is a section on the line 4 4 of Figure 1.

Figure 5 is a section on the line 5 5 of Figure 1.

Figure 6 is a section on the line 6 6 of Figure l.

Figure 7 is a section on the line 7 7 of Figure 1.

Figure 8 is a section on the line 8 8 of Figure 7.

Figure 9 is a diagrammatic view of the hydraulic connections from the tracer controlled valves to the other operative parts of the machine, and

Figure 10 is a diagrammatic view showing the relationship of the tracer finger and supporting parts when the tracer linger is in contact with the pattern.

This invention is an improvement on the construction of tracer mechanisms such as that shown in United States Letters Patent 2,322,533, issued to Roehm on October 26, l943.-

In the tracer control mechanism of the patent the rate and direction of relative movement between two right angularly moving slides of a pattern controlled machine are governed by a pair of rate and direction control valves which are indicated in general by the reference numerals 10 and 11 in Figure 3 of the present drawings. One of these valves, 11, is shown in section in Figure l of the drawings, and it will be understood that it has ports 11a and 11b hydraulically connected to a piston and cylinder for controlling the actuation of one slide; and the other valve, indicated generally by the reference numeral 10, has similar ports connected to a cylinder for controlling actuation of a second slide movable at right ICC angles to the first slide. It has been the custom to arrange the valves in the machine in such relationship that the axis of the valve 11 lies parallel to the axis of movement of its connected slide, and the axis of the valve 10 arranged parallel to the axis of its controlled slide. The valve plungers 12 and 13 of the valves 10 and 11 respectively are continuously urged by springs or the like, such as the spring 14 in Figure l, into contact with control cams or eccentrics such as indicated by the reference numerals 15 and 16 in Figure 1, so that the rotational position of these cams or eccentrics determine the relative position of the two valve plungers and thereby the resultant movement produced by the two slides. It will be obvious that if two slides are arranged at right angles to one another, and one carries the tool and the other the work, and both move at the same rate that the resultant cutting path will be in a direction at 45 degrees to the axis of the two valves.

In the patent and in the construction shown in Figure l the control cams or eccentrics 15 and 16 are annular rings, the ring 15 being engaged by the valve plunger 13, and the ring 16 being engaged by the valve plunger 12, and these rings are anti-frictionally supported on a member 17 which is laterally movable with respect to a xed axis of rotation whereby the eccentricity of the rings may be varied. The member 17 is provided with an annular shoulder 18 which overlaps a flanged member 19 attached to the underside of a gear 20. The gear 20 is connected by a key 21 to the upper part 22 of the rotatable tracer head which is supported for rotation at its upper end by the anti-friction bearing 23. The key 21 also has a spline connection with the oblique cylindrical member 24 which fits in an oblique bore 17 of member 17 whereby axial movement of the member 24 will shift the member 17 laterally. The member 24 has a shifter groove 25 in which is tted a shifter pin 26 eccentrically located on a disc 27 that is journaled on a shaft 28 fitted in a bushing 29 mounted in the wall 30 of the tracer mechanism housing, indicated generally by the reference numeral 31. An operating handle 32 attached to the disc 33 pinned to the outer end of shaft 28 makes it possible to rotate the eccentric pin 26 and thereby, through the connecting mechanism, shift the eccentric members 15 and 16 off center with respect to the ixed axis of rotation of the member 22, and thereby determine the initial port opening effected by the valve plungers 12 and 13 and thus establish the feed rate at which the cutting operation will be performed by the cutting tool of the machine.

As the gear 20 rotates the eccentrics, one valve plunger will be moved toward a port closing position, and the other valve plunger will be moved to effect a greater port opening, and thus the feed rates effected by the two.

valves will be inversely changed, thus eifecting a change in the resultant direction of feed, with the result that a complete rotation of the eccentrics is capable of changing the direction of resultant movement throughout a range of 360 degrees, or in other words, the tracer can completely circumscribe a pattern.

As in the patent, gear 20 is rotated by a hydraulic motor, which is indicated by the reference numeral 34 in Figure 3, of the drawings, and this motor is connected by gearing 35, 36 to the gear 20, all mounted within the tracer housing 31.

By means of this invention a tracer valve is provided shown in Figure 1, is formed in the lower rotatable memhead. -Thefsleeve 38"p'rovidesE a pairfofpressure-ports 42,- dueto the'valve being divided, which are-'connected to a-'source ofpressure, a pair of-moto'r ports -43-and 441* which' arefhydraulically'- connected to th'euhydraulic motorv 34-and a pair of 'exhaustports-45'and 46. In effect, the valve is"areversingcontrol-valvewhich has fbecn shownl diagrammatically in Figure 9, inwhich the valve plunger 37 has afpressurc lport 42, a pairof-motorports and 44lwhic'h'are `connccted'byA suitable channels 47 and 48' to *the'hydrauli'c motor 34 and apair of Aexhaustports 45 and 46. v In nthis view the pressure port A42is connected by a suitable channel 49 toa supply pump 50 having a relief valvev 51. lt'vvillv` now' be obvious. that when the tracer valve plunger37 'isin a central position that the motor 34is stationary, so that any movement of the valve to one .side or the other of its cent'erposition will cause corresponding rotation of the hydraulic motor' in one direction orthe other.

Shifting of the tracer valve plunger 37 is effectedby a crank arm 52 which, as shown in Figure 5, is keyed at 53 to a vertically extendingshaft 54 which, as shown in Figure 1, has .connected to its lower end a second crank arm 55 to which is attached the tracer supporting mechanism shown in Figures 7 and 8.- The lowercrankfarm.

SS 'is' shown in Figure 6,.from whichit will be seen-that a spri1ig56 exerts a continuous urgeon the arm S5, and g thus, inturn, through the shaft, 54 and upperl crank arm 52,wuld normally position the tracer valve 37 in an olfcenter position.V The parts are so oriented that this spring Vis the one. that maintains `a continuous urge on thetracerv linger to maintain` the tracer in contact with the pattern.

The crank ,arm 55 has the lower portion of it-bifurcated byga cross slot, as indicated by thedotted lines 57 and 58,.in1 Figure` 6, thereby forming two dependent arms.

indicated by the reference numerals 59 and 60 in Figure 7.

A tracer linger support 61 is mounted in the cross slot and 1' permanently connectednto a crosswise extending pintle pin 62. which is bearinged at opposite ends in the arms 59 and 60 respectively. The pintle pin forms an oscillatable support for the tracer support and also is capable of'axial sliding movement. one direction-by a spring 63., and an adjustable stop screw 64l-supported byxthearm 60 engages a ball 65 mounted in. a; socket 66 formed. in the end of the pin 621tolimit the extent lof axial movement.

tracer linger; As shown more particularly inFigure 8,

thetracer support 61 has a-depeudentsocket member 67 'f in which interchangeables-tracer lingers-68 areinserted and secured vias by the set-1 screw691sh0wn1inA Figure 1.

The tracer support is capable of--oscillatable 'adjustf' 71- whichY is secured at opposite ends in the 'arms' 59 and 6i) as more particularly'shown in Figure 7.

The purpose of thisadjustment is to advance the tracer finger 68 slightly ahead of its normal vertical position in thedirection of yfeedtoiprovide a slight anticipation of the-'tracer over the `cutter vin following the prole to be copied and compensate `for theslight time delay' between reaction of the pattern on the tracer and the completion of azcorrection movement in the cutter.k These-effects will bebetter understoodnow-'by a general discussion of'y the tracngoperation, because the rotatable .adjustment of the tracery head bears a definite relationzto .the re- Ingother words,.thepin. is urged in- This `adjustment 4is for the.:l purpose of :compensating for anyl difference in size between the diameter of the cutter and the diameter of thel sultant direction of relative feeding movement between the workand thecutter.

As previously mentioned, the two slide control valves 10 and 11 have central positions which have been indicated diagrammatically by the lines 72 and 73 in Figure 3. lf the valve 10 is moved off center in the direction of the arrow 74, it will produce'a movement in the corresponding direction of its connected slide. Similarly, if the valve 11 is `moved olf center in the direction of the arrow 75, it will produce a movement in the corresponding direction of its connected slide. The resultant ofthese two movements will produce a resultant direction ofA feeding movement with respect to the center of the tracer head in the direction of arrow 76. The directional arrow 76 is transferred to Figure 6 whereby it will be seen that the direction of feeding movement is at an angle to the axis of the crank arm 55, which axis is indicated by the line 77. The directional arrow line 76 may be considered a tangent to the pattern `at the point of tracing and therefore the crank arm 55 makes an angle of about A45 degrees to the tangent. condition, especially when the tracer encounters a 90 degree angle in the pattern. It will be noted,'however, that the cross slot in the crank arm 55, indicated'by the dotted lines 57 and 58, is parallel to the direction of feeding as indicated by the arrow 76. Referring now to the diagram in Figure l0, the feeding direction arrow 76 is shown with respect to thesurface 78.0f a patternto be traced. When the tracer finger 68 is adjusted coaxial to the axis of the tracer head, the axis of rotation of the tracer head'would pass through the axis of the tracer linger 68, and this position is indicated by the circle 79 in Figure l0.

As previously explained with. respect to the adjustment effected by the set screw 71, the tracer. finger support can be angularly adjusted about its pintle pin to set the end of .the tracer nger 68 slightly ahead of its normal position, corresponding to the relative position of the cutter with respect to the work, and if this is done the end of the tracer in'contact with the Vpattern would then occupy the position indicated by the circle Stlinthe diagrammatic view in Figure 10, and the distancefbetween the two center lines, as indicated by the reference numeral 81, would kindicate how much the tracer was setahead of the cutter for anticipation purposes. The amount is greatly enlargedy in diagram for explanationpurposes, andas a matter of fact it `is only a fewthousandths'of an inch.

In Figure 6, the normal central position of thetracer finger is indicated by the reference numeral 82, and the axial center of the pivot shaft 54 is indicated by the. reference numeral 83. The center 82vtransferred to the diagram in Figurey 10 constitutes the-center of the circle 79 and thevcenter-SS constitutes the center .0f a circle 84 which corresponds to the center of the pivot shaft 54. It will now be seen thatany reactionon the tracer .circle in Figure 10 toward or from the-pattern will cause a,

swinging movement about the center 83 and thereby rotain Figure 5. This .will cause rotation of the-hydraulic motor and ythereby of the tracer head and through the eccentrics cause a readjustment of the valves 10 and 11v and thereby gradually change the direction of resultant feeding :movement of the cutter. It will-be noted that rotation of the tracer head will move the rock'shaft circumferentially about-the axis'of-the tracer head, and since thev tracer nger on the Alower crank arm 55 is held by the pattern during rotation of the head there is produced a relative rotation between the crank shaft and head which will cause a return shifting movement to the-valve plunger to centralize-it and thus stop/ rotation of the motor'. From thislexplanation it will be'noted-that the tracer ringer. 68 is notsupport'ed for `universal oscillatable movement but for to the-pattern, the ftraeer fingerisunyieldable and there- This gives about thebest tracingA fore is moved by undulations in the pattern to rock the arm 55.

In starting the machine and in effecting initial engagement of the tracer with the pattern, the tracer must be moved in a direction substantially normal to the pattern surface to come into engagement with it, and in so doing the tracer finger would be oscillated or moved backward by the pattern upon contact therewith in a direction to effect compression of the spring 70. The amount of this possible movement is very limited, and the operator would have to be very careful. To protect the tracer from being broken off and to stop the movement if under power controlled by the tracer valve, means have been provided in the form of a pin 84 shown in Figure l which projects from the tracer nger support into engagement with a cam block 85 mounted on the hand Wheel 86 which is attached to the rotatable head as shown in Figure 1. Thus, any backward movement of the tracer finger will cause downward movement of the free end of the pin 84 and since the cam surface 87 is inclined, as shown in Figure 2, it will cause rotation of the crank arm 55 and thereby shift the tracer valve to cause rotation of the tracer head in a direction to relieve the pressure on the end of the tracer finger, preventing i-t from being broken off and placing its plane of oscillation more parallel or tangent to the pattern surface.

In starting the operation of the machine, the operator rotates the hand wheel 86 to position the direction arrow 76 on the spoke 88 of the hand wheel, as shown in Figure 6, to point in the direction of the pattern and then by shifting the eccentrics 15 and 16 off center by rotation of the control lever 32, fiuid pressure is connected through the control valves 10 and 11 to the respective slide cylinders, causing relative movement to take place between the tracer and pattern to move the tracer into engagement with the pattern. It will be noted that the spring 56 shown in Figure 6 is normally active to maintain the tracer valve in Figure off center, which would cause continuous rotation of the motor 34 and thereby of the tracer head, but the operator at this time has the hydraulic pressure disconnected from the tracer valve through suitable valving well known in the art, or even by stopping the pump. When the tracer engages the pattern, fiuid pressure is connected to the tracer valve, and it takes over and readjusts the position of the parts until the plane of oscillation of the tracer moves into parallelism with the pattern, after which the tracer will automatically follow around the profile.

Another feature of this invention is that since the tracer finger is held substantially rigid, it is possible to utilize it also to actuate a depth control valve at the same time it is following a profile. This is accomplished by mounting the rock shaft 54 for axial movement and frictional resistance is removed as far as possible by mounting the rock shaft in a tube 89 containing anti-friction balls 90. A depth control valve plunger 91 is mounted in a valve sleeve 92 in the upper part of the tracer housing 31, and as shown in the diagram in Figure 9, has a conventional pressure port 93, motor ports 94 and 9S which are suitably connected to a hydraulic cylinder 96 having a piston 97 operatively connected for moving the tracer head toward and from a contoured surface substantially normal to the surface which the tracer finger 68 engages laterally. The valve also has a pair of exhaust ports 98 and 99 which are suitably connected to reservoir. Thus, any vertical movement of the valve plunger up or down from a central position will cause actuation of the piston 97.

The valve plunger 91 is normally urged downward by a spring 100 into engagement with the end of a rod 101 which is slidable through the center of the rotatable member 22. The lower end of the rod interfits in a radial slot 102 of an arm 103, mounted for free rotation on the reduced end 104 of the rock shaft 54 in the sense that the arm 103 is held against rotation by the rod 101 so that the end of the shaft 104 rotates relative to the arm 103. This permits the rock shaft 54 to oscillate without causing oscillation of the member 103.

The spring maintains the valve in engagement with the rod 101 and thereby through shoulders 105 on the lower end of the rod pushes against the member 103 and maintains it in engagement with the top side of the crank arm 52. The crank arm 52 can move downward with the rock shaft 54 a small amount limited by the surface 106 on the underside of the crank pin engaging the top surface of the tube 89.

A counterbalancing spring 107 is connected to the rock arm 55 by a pin 108 and the other end of the spring is connected to a pin 109 in the rotatable tracer head. This tends to counterbalance the weight of the parts and thereby relieves the pressure between the end of the tracer and the pattern. The tracer will be pushed up by the pattern sufficiently to centralize the valve plunger 91 and from then on any rise or fall in the contour being followed will effect a corresponding movement of the depth control valve which, in turn, will cause a corresponding vertical movement of the tracer head.

It is obvious, of course, that two directional control tracing may be desired at times without the depth control feature, which can be accomplished by divorcing the depth control feature while at the same time holding the piston 97, shown in Figure 9, in fixed position. The circuit connections for accomplishing this are outside of the tracer mechanism of this invention, and are not part hereof, but such connections are old and well known in the art, and one way of making such connections are shown in Figure 7 of the patent to I. C. Campbell, No. 2,039,294, issued May 5, 1936.

There has thus been provided an improved tracer mechanism which utilizes a single tracer finger to control three directional movement between tool and work, and which is so constructed that the weight of the two directional valve is ineffective as a factor in determining the pressure between the tracer and the pattern whereby irnproved tracing conditions can be obtained.

What is claimed is:

1. A tracer mechanism comprising a housing, a rotatable tracer head journaled in said housing, fiuid operable means connected for rotation of said head, a tracer valve mounted in said head having a source of pressure connected thereto, said valve having a plunger movable from a neutral position to connect said source of pressure to said fluid operable means, and pattern operable means to control the shifting of said plunger including a rock shaft eccentrically journaled in said head parallel to the axis of said head, a crank arm operatively connecting said rock shaft to said plunger, a second crank arm attached to said rock shaft, a tracer finger attached to said second crank arm in offset relation to the axis of the rock shaft whereby lateral movement of the tracer finger will rock said shaft to open said valve and cause rotation of the head.

2. A tracer mechanism comprising a housing, a rotatable tracer head journaled in said housing, fluid operable means connected for rotation of said head, a tracer valve mounted in said head having a source of pressure connected thereto, said valve having a plunger movable from a neutral position to connect said source of pressure to said fiuid operable means, and pattern operable means to control the shifting of said plunger including a rock shaft eccentrically journaled in said head parallel to the axis of said head, a crank arm operatively connecting said rock shaft to said plunger, a second crank arm attached to said rock shaft, a tracer finger attached to said second crank arm in offset relation to the axis of the rock shaft, and resilient means operatively connected to said shaft for maintaining a rotational urge thereon to main tain engagement of the tracer finger with a pattern whereby lateral movement of the tracer finger will rock said shaft to open .said valve and' cause'rotation of the head.`

3. A tracer mechanism comprising-.a housing, a rotatable tracer headzjournaled in said housing, fluid operable means connectedforrotation of said head, a tracer valve mountedin said head having a source of pressure connected thereto, said valve having a plunger movable from a `neutral position to connect said source ofpressure to said fluidoperable means, and pattern operable means to control the shifting of said plunger including a rock shaft eccentrically journaled in said head parallel to the axis thereof, a crank arm operatively connecting said rock shaft to said plunger, asecond crank arm attached to said rock shaft, a Ytracer linger attached to said second crank arm and lying in said plane whereby lateral movement of the tracer finger will rocksaid shaft to open said valve and cause rotation of thehead.

4. A tracer mechanism comprising a housing, a rotatable-tracer head journaled in said housing, fluid operable means connected for rotation of said head, a tracer valve mounted in said head having a source of pressure connected thereto, said valve having a plunger movable from a neutral position to connect said source of pressure to said fluid operable means, and pattern operable means to control the shifting of-said plunger including a rock shaft eccentrically journaled in said head parallel to the axis thereof, a crank arm operatively connecting said rock shaft to said plunger, a second crank arm attached to said rock shaft, a tracer finger attached to said second crank arm and positioned thereby co-axially with the tracer head axis when saidvalve plunger is in a neutral position.

whereby lateral movement of the tracer finger will rock said shaft to open said valve-and cause rotation of the head.

5. A tracer mechanism comprising=a housing, a-rotatable tracer head journaled in said housing, iiuid operable means connected for rotation of said head, a tracer valve mounted in saidhead having a source of pressure connected thereto, said valve-having a plunger movable from a neutral position to connect said source of pressure to said tiuid operable means, and pattern operable means to control the shifting of said plunger including a rock shaft journaled in said head parallel to the axis of the head, a crank arm operatively connecting said rock shaft to said plunger, a second crank arm attached to said rock shaft having an axis intersecting the axis of said head when said valve plunger is in a neutral position, a tracer finger, means on the axis of said crank arm at the point of said intersectionto support said tracer finger on said rock shaft co-axial with the tracer head axis, said supporting means including a pivot providing angular adjustment of said tracer-finger in .a plane `angularlyrelated to aplane passing through the axis of the tracer head and rock shaft to advance thepattern contacting end of the tracer finger relative to the axis of said tracer head.

6. A tracer mechanism comprising a housing, a'rotatable tracerhead journaled in said housing, fluid operable means connected for rotation-of said head, a tracer valve mountedin said head having a source of pressure connected thereto, said valve having a plunger movable from a neutral position to connect said source of pressure to said liuid operable means, and pattern operable means to control the shifting of said plunger including an oscillatable shaft supported in the head parallel to theaxis of said head, a crankarm operatively connecting said shaft to said plunger, a second crank arm attached to saidv shaft, a tracer finger, a support for said tracer finger mounted on said second crank arm by a pivot pin journaled therein, with its axis lnormal to said feeding direction, meansto adjust the tracer linger support about said pivot pinto advance the pattern contacting end ofthe tracer linger ahead .of said pivot pin, means acting on said shaft to maintain contact of the tracer with a pattern whereby lateral movement of the tracer will oscillate said shaft to open said valve and cause rotation of the head.

7. A tracer mechanism comprising a housing, a rotatable.tracer headjournaled in said housing, fluid operable means connected for-rotation of said head, a tracer valve mounted in said head having a source of pressure connected thereto, said valve having a plunger movable from a neutral position to connect said source of pressure to said fluid operable means, a second vvalve mounted in. said housing co-axial with thev axis of said head, and means to .control the shiftingvof said valves including a rockshaft journaled in said head parallel'to the axis thereof for rotary and axial movement, acrankarm operatively connecting said rock shaft to said valve plunger for imparting movement thereto upon rotation of'said'shaft, asecond member responsive to axial movement of the shaft for actuating said second-named valve, a second crank arm attached to said rock shaft, a tracer lingerattached. to said second crank arm inotTset-relation to the axis of the rock shaft whereby lateral movementof the tracer finger will operate the first-named valve and axial movement of the tracer finger will effect movement of the `second-named value.

References Cited in the file of this patent UNITED STATES PATENTS 

